There's a Heifer in Your Tank

Why can't horses throw up?

 

First, in answer to the question, “Can horses throw up?” NO, they cannot throw up. But did you ever wonder why? Well our team at the University of Alberta has researched this question and came up with a detailed response.

When a horse first ingests food, it is swallowed through the mouth cavity and is passed down the esophagus. Horses have a strong band of muscle around their esophagus at the entrance to the stomach, called the “cardiac sphincter” also referred to as the “esophageal sphincter”. The cardiac sphincter is actually the strongest sphincter muscle of all species. The cardiac sphincter exists in all mammals at the top of the stomach, and in the horses it differs from other mammals because of its extreme strength and inability to relax and allow the horse to throw up like other mammals. As stated by Dr. Susan Novak, the AAFRD(Alberta Agriculture Food and Rural Development) Provincial Horse Specialist, “The horse is not able to throw up because the cardiac sphincter connecting the esophagus and stomach is so strong, that food is only allowed to go in one direction: Down! The horse is adapted to eating small frequent meals, and therefore the sphincters work to keep the feed moving constantly along the digestive tract.”

 

It seems the horse is at an advantage because it cannot throw up. First, the stomach of the equine species is very acidic like any other species. Second, this action of the cardiac sphincter and the pyloric sphincter at the exiting end of the stomach allow for the continual movement of the digestive system in the right direction, and prevent any backups, which could be very detrimental to the horse, causing conditions including colic. Horses are very instinctive and will usually avoid harmful feed that could cause them to become ill.

Since it is impossible for a horse to throw up, there is no way for anything to escape the stomach. As stated by Dr. Lana Bissett, from the Edmonton Equine Veterinary Services, “Cases of horses having spontaneous reflux is uncommon.” Based on the anatomy of the cardiac sphincter it will rarely release and because it so strong that the stomach lining will rupture before the sphincter gives way. This is a bad situation for horses and after the stomach has ruptured the horse will die.

There is something you can do for a horse once you’ve noticed that it’s showing colicky symptoms. But the procedure must be done quickly before the stomach lining ruptures. The procedure is known as tubing. A trained veterinarian must be contacted to tube the horse, and should not be attempted by the owner, because it is very easy to make a mistake. The vet will pass a tube (stiff with a bulb on the end) nasogastrically (through the nose) down the esophagus, and pass it through the cardiac sphincter, as stated by Dr. Lana Bissett, “Tubing, works well as it forces the sphincter open which releases the pressured contents, usually gases and sometimes fluids will be released right away or after gentle siphoning. Recovery is usually favorable (depending on the condition).”

- Shanna Hlady, Melissa Kozakewich and Lindsay Paulsen

Oh, sweet milk letdown

How many four-litre jugs of milk can a cow produce in a day?

 
Got milk? Bessie does–a lot of it. How much depends on many different factors, ranging from environmental to anatomical.

Bessie is an average Holstein cow from Alberta. She has a calf and milks for 305 days of the year. Her maximum milk production occurs around two and a half months from the beginning of her milk cycle. At this peak she may be able to produce as much as 45–50 litres of milk a day.

 

According to Mike Murphy, a dairy farmer from Calmar, Alberta, one of “[his] cows milked out 55 litres during her peak lactation.” Milk production then declines steadily to an average of 28 litres per day before entering her dry period on day 305. Bessie can be milked two or three times each day depending on the personal preference of the farmer. Michael Lovich, a dairy farmer from Sangudo, Alberta, states that he “prefer[s] to milk [his] cows two times each day but if [he] had the help [he] would milk them three times each day for an approximately 15 percent increase in milk production.” He claims that milking two times a day can cause more stress on the udder as it would be fuller than if you milked three times a day.

Farmers often wonder what affects the milk production of their cows. An important factor is the type of food Bessie eats. A lactating cow that is fed a total mixed ration will usually have higher milk production compared to one that is fed only grain or pasture. The total mixed ration consists of vitamin and nutrient additives as well as the basic protein and fibre needs of a cow. Diet affects milk production, as does body condition score (BCS). If Bessie has an ideal body condition score she will be able to produce a larger quantity of milk than if she did not. In addition to feed and BCS, age also affects Bessie’s ability to produce milk. The average dairy producer allows a cow to continue milk production for 3-4 years. A cow produces the most in her third lactation with a steady decline thereafter.

Older cows are also more susceptible to infections of the udder. Mastitis is an inflammation of the tissues of the udder, measured by the somatic cell count. Mastitis is common in bacteria-ridden barns and produces thicker milk with a yellow tinge. But don’t worry, this milk is not going to end up in your cereal.

Sanitation in the dairy industry is extremely important. One way that farmers ensure the safety of our milk is by dipping the teats before and after milking in a liquid solution of iodine. Once the teats are pre- dipped, the farmer will wipe them clean with a cloth and attach the robotic milkers. This routine of pre-dipping also helps to stimulate the letdown of milk. The hormone that controls this milk letdown is oxytocin, which is released from the anterior pituitary gland in the brain.

So do you think that you could drink all of the milk one cow produces in a day? Not unless you are really thirsty. On average a cow will produce 28 litres of milk in one day, which is seven four-litre jugs of milk or 112 glasses. However, during peak production times, 45–50 litres of milk are produced in one day. That can be converted to 11–12 four-litre jugs or 180–200 glasses. That is why everyone can get the wholesome goodness of milk at a fair price, and will be able to for years to come.

- Carmen Bell, Fawn Jackson and Jake Murphy

Bigger isn't always better- inside out ovaries in horses

 

Men are from Mars, and horses are from Venus. No no, horses are not aliens. However, the structure and behavior of their ovaries is like nothing else on earth. Due to the mysterious wonders of evolution, horses have evolved many unique characteristics. Horses cannot vomit, their ovaries appear to be inside-out and they have some of the largest follicles of all mammals. These characteristics are just some of the strange and fascinating qualities of the horse’s reproductive system.

Follicles are the sack-like structures of the female ovary where eggs grow and mature. In human ovaries the follicle grows on the outside of the ovary; however, in mares the follicle grows deep within the organ. Since the follicle grows near the middle, in order for it to be released the ovary must remodel itself. The follicle is released through the ovulation fossa, causing no harm to the surface of the ovary. The large size of the follicle gives no structural advantage, if anything it makes ovulation more difficult. 

 

Mare’s ovaries appear to be inside-out compared to those of humans. Like a shirt inside-out still keeps you warm, an ovary inside-out still functions. In human ovaries, the outermost part consists of the cortex and the inner part the medulla; in the mare, the medulla surrounds the cortex, while the ovulation fossa is located in the center of the ovary. The ovulation fossa allows the ovary to still ovulate; therefore, the internal structure has little effect on the organism’s ability to reproduce. Fertilization occurs in the oviduct. Humans experience symptoms of pregnancy such as morning sickness shortly after fertilization.

 There is a one-way valve between the stomach and the esophagus of both the human and the horse that prevents food that is already in the stomach from going back up. In humans this valve doesn’t always work, while in horses the power of this valve makes it physically impossible for the horse to vomit. Hence, in a horse the stomach will rupture before the valve gives in. This results in colic, which is severe abdominal pain caused from an extreme build-up of food, acid and gas in the intestines. As a result of this powerful one-way valve a mare will not show symptoms of morning sickness during pregnancy.

The mare is designed to support only one fetus; however, this doesn’t mean that twinning will never occur. It occurs only rarely, when multiple ovulations happen from either one or both follicles. When two foals are born they tend to be considerably smaller and less developed, which often results in the death of both foals. Quite often humans take ovulation- enhancement drugs which cause rapid release of eggs during ovulation. This increases the chance of getting pregnant since it is more likely that an egg will be in the fallopian tube when the deposit is made. It also increases the likelihood of twins, triplets, even octuplets, for the ovary will release more eggs. However, these ovulation promoting drugs have little effect on horses.

The mysterious ways of evolution have made reproduction in horses a distinctively unique process. While very different from a human, the mare's reproduction is every bit as functional. The inside-out ovary, when compared to the ovary of a human, makes ovulation of one of the largest follicles in the animal kingdom a miraculous feat. The whole interior of the ovary is forced to rearrange itself in order to let the follicle move to the surface and be released. Once fertilization occurs, morning sickness can not be used as a determinant for pregnancy for one of the main symptoms of the sickness, vomiting, does not happen in horses. So horses really aren’t from Mars or Venus. Their basic ovulatory cycle makes them as down to earth as every other mammal.

 - Christina Carley, Mike Mielke and Janine Swenson

Ruminating on teeth

 

How can one understand the digestive system of a cow without knowing exactly how many teeth she has? A simple number can give us a better understanding of digestion, if we know a bit more about these teeth. Cows have 32 teeth, just like humans do. What is interesting is where these 32 teeth are distributed and why. We all understand the functions of our own teeth, front teeth are for biting and back teeth are for chewing, but what does a cow do since she has no upper front teeth?

 
A cow’s teeth are distributed much differently than a humans’ teeth are. Unlike humans, cattle can be born with or without teeth. When they obtain their permanent teeth, after 30 months, they have 12 premolars top and bottom, 12 molars on top and bottom, and only 8 incisors which are all found on the bottom of their mouths. Instead of upper incisors, a cow has what is called a dental pad, a patch of tough skin covering their gums.

At first glance it would seem that missing front teeth would be rather inefficient when it comes to eating, especially since cows can eat up to 100 pounds of grass per day. But the cow’s mouth is only one of the many parts of the digestive system. A cow’s stomach is separated into four different compartments, the first of which is the rumen. The rumen helps compensate for front teeth in digestion, further reducing the size of food particles.

When cows eat, they use their tongues to wrap around grass and their lower incisors to cut it. They swallow grass mostly unchewed. The swallowed grass will enter the rumen for a short time but then it is pushed back up through the esophagus and into the mouth, where it is chewed and re-chewed. This process, called cud chewing, is repeated for 6 to 8 hours. While the food bolus, or cud, sits in the rumen, the fibre is being broken down by resident bacteria and protozoa into fatty acids and absorbed through the rumen walls. The process of chewing cud and breakdown in the rumen decreases the particle size of the grass, making the chopping function of front teeth unnecessary. If you happen to see a cow in the pasture seemingly chewing on nothing, it is actually chewing on its cud.

Cattle aren’t the only ones that have a dental pad in place of upper incisors; most ruminants share the same dentition. Sheep, goats, deer, and even camel have teeth which are similar because they are ruminants and their rumen works to perform the function of upper incisors. Horses, on the other hand, are monogastrics, meaning they do not have a  compartmental stomach and rumen. It is only logical then that horses don’t share the same dentition – they have upper incisors. By looking at an animal's mouth, you can tell what kind of stomach it has. Animals with no upper incisors can be assumed to be ruminants.

We can expect that if we brush our teeth twice a day we’ll be able to keep our 32 teeth until the day we die. Cows, however, can find themselves without teeth after only 10 years of age, a condition known as peg teeth. Normally cows do not reach the stage where they develop peg teeth as they are sent to market well before then. Although, as Dr. Reza Khorasani, the manager of the University of Alberta Dairy Research and Technology Centre explains, “[they] do see wear occurring on the teeth of [their] cattle.

Due to the large amounts of chewing a cow does, approximately 40 to 60 thousand jaw movements a day, their teeth are continually wearing down. This wear is consistent with most cattle and can be used to determine their age. However, according to Dr. Craig Wilkinson, a veterinarian and Director of Animal Care at the University of Alberta,

“After two years [teeth aging] becomes a very rough estimate [of age.]” Cows' mouths are not particularly prone to problems beyond terminal wear although Dr. Wilkinson points out, “They also occasionally get other problems such as broken teeth, or abscesses ... when cattle develop dental problems they are most often culled, then diagnosed.”

 

Although cows and humans may share the same number of teeth, their mouths have little else in common. Teeth placement and function are related to the digestive system of an animal. The cow’s compartmental stomach, specifically the rumen, takes the place of upper teeth. Don’t be alarmed if the next cow you see is apparently missing its front teeth or is chewing nothing for hours on end; she is just doing what all ruminants do best with what they have.

- Tyson, Bieleny, Sara Dargis, Kari-Ann Roveredo and Liz Simpson

Just a spoonful of sugar...

Why can sugar help your litty piggy's rectal prolapse?

Producing animals efficiently is not an easy job. Farmers face many problems in raising livestock. Swine farmers in particular, have had to learn how to deal with rectal prolapses. Believe us, it is not very nice.

A rectal prolapse occurs when a pig’s rectal walls fall out of place due to the breakdown of the muscles that support the pelvis. This occurs because of increased abdominal pressure. Environmental and/or nutritional factors may be the cause of this type of prolapse. Problems with feed, such as being ground too fine, spoiling by fungal toxins, or having high lysine (an amino acid in proteins) content, are major contributors to prolapses. Constipation or diarrhea, huddling and piling for warmth, coughing, complications in farrowing (giving birth), and docking tails too short (resulting in a snipped sphincter) are also factors that may lead to rectal prolapses.

What can be done to solve this problem? Normally in this type of situation, a veterinarian would want to surgically place the rectal tissues back inside the pig, then pull them together and close the anal opening with a purse-string suture (a continuous circular fibre). This procedure can be very costly and time consuming. What the veterinarian does not tell you is that common table sugar can help you in your effort to replace the prolapsed tissues. However, the use of sugar in this situation is considered to be a folk remedy. Mary Poppins may have been right after all.

 

Why does sugar help? A spoonful of sugar (or in our case a bowlful) helps the swelling go down. Sugar creates an environment where the solute concentration is greater on the exterior of the rectal tissues than inside of the cells that make up these tissues. Due to laws of osmosis (figure 1), water will passively move out of the rectal tissues and across the cell membrane. The cell wall is impermeable to sugar due to its stable and complex nature. This results in the shrinkage of cells, which will aid the farmer in pushing the less inflamed rectal tissues back inside the anus.

In addition to using sugar, it is important to give the affected pig antibiotics to prevent infections and painkillers to reduce discomfort. It is also essential to give laxatives to keep that colon flowin’.

Many sheep, cattle and swine producers have used or are using sugar to help the rectal prolapses of their animals, although the problem is not very common except in sheep. Sugar is a very cost efficient method of helping to reduce the severity of the situation and in the words of Murray Markert, a swine producer from southern Alberta, “It really works!” Tova Place, an employee of Mr. Markert, told us “Over the last ear, three (of six) sows have responded well to the sugar treatment and were able to farrow and nurse their litters.” Considering the alternatives of surgery or putting the animal down, a 50% success rate seems to be significant enough to continue using this method. Bring on the folk remedies.

- Shari Smith, Naomi Fisher, Suzan Sidra and Mathew Matras

The facinating world of extra nipples

The lowdown on extra teats in cattle

 

 

Did you know that cows can have extra teats? Many people believe that cows only have four teats; however, approximately 50% of cows have one or more extra teats.

Most accessory teats have a slightly different structure compared to regular teats. They are usually smaller and located at the back of the udder.

An udder is divided into four sections called quarters. The inside of each quarter is filled with tiny sacs known as alveoli, which are responsible for milk production. Alveoli release milk into the gland cistern, a “storage tank” in the udder. The process when milk is released from alveoli is commonly referred to as milk letdown, which can take 10 to 20 seconds to occur. After milk has been released it travels through the nipple to the outside world.

In theory, an extra teat could be a great way for farmers to increase production; however, this is not the case. Extra teats have little impact on milk production. Most extra teats have no alveoli to produce milk, or they are not connected to a quarter. Occasionally, dummy teats do produce a small amount of milk, but it is not enough to significantly increase production.

A fifth teat can be looked at in a similar fashion to a third nipple in humans. To some farmers, it is just a blemish and is of no concern, but others will have them removed. Harry Koeckhoven, a Stony Plain dairyman stated “It’s ok to have a fifth tit in the parlor, but not in the show ring.” Harry has similar ideas to beef producers. When asked about extra teats, Ken Rutledge, a rancher from Hardisty commented, “The fifth tit serves no purpose in the beef herd. The calf is unable to suck it because it is too small and it produces little or no milk. In a purebred herd extra tits can be snipped off with a sharp knife when the calf is a day old. When the heifer freshens she will have  a nicer well balanced udder.”

Removing an extra teat eliminates one possible site of infection, since any unused cavity is ideal for bacterial growth. Also, if extra teats get large enough they can interfere with the milking machines so removal is sometimes necessary. Fifth teats are often removed on show cows since they are considered unwanted blemishes in the show ring, which could cost you the red ribbon. The removal of an extra teat does not affect milk production or the cow’s growth and development. Removal is more for convenience or aesthetics.

The removal of extra teats should be done when a calf is less then three months old. The teat being removed is cleaned, and then cut off with clean sharp scissors followed by the application of disinfectant to reduce the chance of infection. By properly removing an extra teat pain is minimal and healing is fast.

Fifth teats or extra nipples are not only seen in cattle, but in many other animals. All mammals can have extra nipples. Unfortunately they can be seen in both males and females.

- John Koeckhoven, Tess Rutledge, Kelsey Shaker and Tina Shih

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